You need to get Obsidian Rings in Genshin Impact to lower the barrier of each tribe's secret trove area. These secret areas are worth unlocking, as they contain useful rewards like 5-Star ...

In Tales of the Green Lantern Corps Annual #3's story "In Blackest Night" by Alan Moore and Bill Willingham, Katma Tui is sent to a pitch-black sector of the universe known as the Obsidian Depths ...